MISCELLANEOUS PAPERS. 393 



rumble began to be felt and heard. The noise increased to a loud 

 roar as the train sped away to the east and only ceased when the train 

 stopped at Ellinwood, four miles distant. Even after the train started 

 up again the rumble could be heard, though gradually growing fainter 

 as the train neared Raymond, twelve or fifteen miles distant. 



The other form of reflecting mirage is where objects on the earth 

 are reflected into the sky. This is caused by the air becoming strati- 

 fied. On such occasions distant objects in the observer's stratum are 

 seen inverted in the sky, reflected at a very high angle of incidence 

 and reflection from the surface of the stratum overhead. The angle 

 of reflection on such occasions is usually 89J degrees, or even more. 



A far more important form of mirage — one that occurs always in 

 clear, cold weather, and all over Kansas — is of the pure refracting 

 kind. This usually occurs in the evening, at night, or in the morn- 

 ing, when the air is comparatively still and the cold air settles down 

 into the valleys. On such occasions the cold air flows, like water, from 

 its own gravity, down into the lower ground. The rate of flow, when- 

 ever noticed, is about 2 miles per hour. When the rate exceeds 

 4 miles per hour, the proper refraction of the rays of light is dis- 

 turbed and the beauty of the vision is destroyed. I say "beauty of 

 the vision," because it is always beautiful, grand, exalting, entrancing. 

 To be able to see, when you are living in a broad, shallow valley, 

 across the distant hills into another valley, and to see distinctly the 

 houses, with the smoke arising gently from them, and to see the young 

 groves and other large objects in their natural positions, when you 

 know that the elevated prairie between you and the objects seen is at 

 least 100 feet above your level, is exhilarating beyond conception. 



For six years — from 1874 to 1880 — I lived in Barton county, Kan- 

 sas, and kept a weather record during all that time. Observations 

 were recorded thrice daily on temperature, humidity, rainfall, wind 

 direction and velocity, and clouds. On looking up my old record for 

 notes concerning mirage, I find during winter, on an average of about 

 twice a week, this note: "Mirage at sunrise." Notes like these: 

 "Strong refracting and reflecting mirage at sunrise," etc., "mirage to 

 north at sunrise," "mirage at sunset," "very strong mirage," etc., oc- 

 cur about once a month or less frequent. Ellinwood is in the middle 

 of the Arkansas valley, about 10 feet above water-level in the river, 

 with a horizon so low to the north and south and west that it seems 

 like being on a dead-level prairie or an ocean of grass. Very low up- 

 land is to be seen northwest and east, and higher sand-dunes to the 

 southwest. The first mirage of the refracting kind within my ob- 

 servation was in the fall of 1874, while teaching at Ellinwood. 



The occasion was before sunrise on a calm, clear, frosty morning. 

 The sight was most beautiful and inspiring. The land to the north 



